The backend couldn't read Tor hidden service hostnames because the
systemd service only had SupplementaryGroups=dialout. Adding debian-tor
allows the backend to read /var/lib/tor/hidden_service_*/hostname
without needing sudo (which is blocked by NoNewPrivileges=yes).
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>